Heat alarm system



April 5, 1938. p. F. KRO@- HEAT ALARM SYSTEM Filed July 25, 1935 AHarney Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE 1 Claim.

This inventionrrelates to a thermostatic or heat operated switch, thegeneral object o the invention being to provide a heat operated switchof superior simplicity and ruggedness, which is 5 readily adjustable tooperate at different temperatures.

Other important objects of my invention will be apparent from a readingof the following description in connection with the drawing, wherein forpurposes of illustration I have shown a preferred embodiment of myinvention.

In the drawing:-

Figure 1 is a transverse vertical sectional view taken through thethermostatic device.

Fig. 2 is a side elevational view of Figure 1 taken from the leftthereof.

As shown in the drawing, the switch 22 comprises the tubular metallicpart 24 which has a relatively reduced bore 26, the lower end leadinginto one side of the upper part of a cylindrical chamber 2l which isarranged with its axls horizontal. The chamber 2l is formed in asectional block composed of the upper section 28 integral with the tube24 and the lower separable section 29 which is assembled to the uppersection by means of bolts 30 which traverse the side walls of thechamber as indicated in Figure 2. The tube 24` is conveniently arrangedthrough an opening in a support 3l.

A binding post screw 32 traverses the side of the tube 24 below theenlarged bore portion 35 and is in contact with the mercury 33 whichfills the interior of the chamber 21 and the tube 24. The binding post32 is provided for convenient connection with the regular house current.

Inserted into the enlarged bore portion 2l is the vitreous insulatingmaterial tube 34 preferably of glass or the like and this is held inplace by a cap 35 which is threaded on the exterior of the upper end ofthe tube 24 and contains a packing 36.

On the upper end of the insulating tube 34 is telescoped a dielectricblock 3l in which is axially mounted a bushing 38 which is bothexteriorly and interiorly threaded, exteriorly to receive the 45 bindingpost nuts 39 and interiorly to receive the electrode which is', byvirtue of this arrangement vertically adjustable in the bushing 38. Itis obvious that by adjusting the electrode 40,

(Cl. 20o-141) the height to which the mercury 33 must rise to makecontact with the lower end of the electrode 40 is predetermined, and bythis arrangement, the switch is adjustable to operate at a considerablerange of temperatures. For convenience gauge markings 4I on the exterioroi the translucent dielectric tube 34 are placed at vertical intervalsand designate degrees of temperature and at the same time the height towhich the mercury will rise at a corresponding temperature to engage thelower end of the electrode 40. The mercury is clearly visible so thatits height may be compared with the various gauge markings.

Although I have shown and described herein a preferred embodiment of myinvention, it is to be denitely understood that I do not desire to limitthe application oi the invention thereto, and any change or changes maybe made in the materials, and in the structure and arrangement of theparts, within the spirit of the invention and the scope of the subjoinedclaim.

What is claimed is:

A mercury switch comprising a casing formed of upper and lower sectionsdetachably connected together and forming a horizontally arrangedcylindrical chamber, a vertically arranged tubular part connected withthe upper section and having the lower end of its bore entering thechamber at one side and below the top thereof, the upper part of thebore of the tubular part being enlarged, a transparent tube having itslower end tting in the enlarged part of said bore, packing means forholding said end of the transparent tube in position, a block ofnon-conducting material fitting over the upper end of the transparenttube, a metal sleeve having its lower part `fitting in the block andcontacting the upper end of the transparent tube, the sleeve beinginternally threaded, a rod having a threaded part passing through thesleeve, with its lower part located in the transparent tube, the upperpart of the sleeve being exteriorly threaded, nuts on said threadedpart, and a contact member carried by the tubular part of the casing andcontacting the mercury in the reduced part of the bore of said 5

